Air or gas compressor



April 25, 1939. w. F. JENNINGS 2,155,551

AIR OR GAS COMPRESSOR Filed Oct. 14, 1956 ATTORNEY Patented Apr. 25, 1939 UN'iTE-D STATES PAT EFNTT OF F 1 CE Applicationiioctoben --1-4, 1936, ;Serial No." 105,606 I In Great Britain-Octoberlb, 1935 4 Claims.

This invention relates to improvementsin aire, or gas: compressors and has .i'or its objecthimproved means for transferringltheacompressedzair or gasfrom the first or lowpressure -cylinders :to thesecond or high pressure cylinders from.

whence the compressed airor gas'is -discharged;;,. with means. for cooling the air or gas so trans ferred, the arrangements-generallytending-to increased eificiency, and silent running of the machine at high speed.

With theusual method of operating two-stage; compressors at the presentntime it is essential to employ in eachpair of low and high pressure cylinders at least four valves, two suction valves andtwo delivery valves, either of the spring urged ring valve or poppet valve type, which are always a potential source. of trouble and necessitate a considerable amount ofclearance in both the low and high pressure cylinders thereby decreasing the volumetric eihciency of the compressor.

To overcome these disadvantages; in the present-invention,threeof the four valves referred to above are eliminated by the employment-of a single reciprocatingsleevevalve with ports" to control the air or gas inlet to the low pressure cylinder and the discharge of the partially compressed air or gas iromthe lowpressure cylinder, either direct or through an *intercooler, into the in the cylinderwall, which are'uncoveredby the fiat-top high-pressure piston at the bottom of its stroke, then further compressed-to its finalpressure by theflattop high pressure piston onthe upstroke/and discharged through the automatic springcontrolled delivery valve 1 situated in the cylinder cover Theintercooler-aforesaid may be a separate" entity of anywell known type disposed outside -=-the machine or as in one specific construction embodying the invention, hereinafter described and illustrated by way of example the partially compressed-air-or gas maybe cooled during transfer by passage through a coil immersed in the I cylinder jacket water.

An air or gas compressor according to the present-invention therefore comprises a pair of superimposed cylinders with superimposed trunk pis-- tons-the low pressure cylinder being fitted with 50 ,a single reciprocating sleeve valve having inlet 7 e and outlet ports and the high pressure cylinder withainletports in the cylinder;.walls'and-an automaticgdeliverycvalvepin the cylinder-cover.- 1:

The invention is applicable-to two-stage airz;v

,or g-asrcompressors of either thesingleor multi.-.

high pressure cylinder, through a series of ports cylinder type. Whenrembodied in a two stage. air or gas compressor of the multicylinder-type; as in the examplerhereinafterdescribed andillustrated, comprising pairs-of superimposed low and high pressure cylinders disposed-side by side,.' thevsleeve valves, in association .with': the low pressure cylinders, control therair or gas inlets to the low pressure cylindersandvthe discharge of thexlpartially compressedtair or gas vfromthe low pressure cylinder, of onepair of cylinders to 10 the high. pressure cylinder of the, other pairand 1 from the low pressure cylinder of thellatter:

pair to the high pressure cylinder of the first. pair of cylinders through inlet ports in the lower I ends of the. high pressure cylinders which are uncovered by thehigh pressure pistons at the bottom of their strokes, the. partially compressed air or gas which in the course of its vpassage from: the low to the high pressure cylinders passes through coils immersed in the vwaterof the cylinder jackets, being furthercompressed in the-highpressure cylinders to its final pres? sure by the high pressurev pistons on their up strokes: and discharged through. the automatic y delivery valves in the cylinder covers.

Theinvention also includesa modification of the two stage compressor, wherebyit may oper-.= ate'as a three-stagecompressor, with the working capacitynotlimited to the volume of the low pressure cylinder or cylinders-butt increased to thefullvolume of both the low an-dhigh pressure cylinders.-

But in order that the-invention may -be more clearly understood referencemay now be made to the' accompanying drawingillustrating by way of example a sectional elevation, partly broken away,--of anair or'gascompressor of the multicylinder type with the improvements applied thereto.

Referring to the drawing it will be seen that in the example illustrated the compressor body comprises two main cylinders formed by the out-' er walls a and b and the common intermediate wall'c and liners d and e are-inserted in these two cylinders, the lower parts of which'with their liners provide the low pressure cylinders'f andg. The high pressure cylinders'h and i-above the low pressure cylinders f and g are formed in dependences from a heavy' eover k by which a joint is made with themain-cylinders and the liners d, e. The low pressure pistons land m carry extensions. on their upper surfaceswhich serve as the highypressure' pistons n and o.

The sleevesyalvesp and q are inserted betweenthelow pressure pistons Z and m andthe low pressure cylinders j and g and are reciprocated in the usual manner by means of eccentrics from the crank shaft, the cranks of which associated with the pistons l and m are arranged in opposite directions so that when the pistons Z and n are at the bottom end of their stroke the pistons m and o are at the top of their stroke.

The main air or gas inlet ports r r in the liners d and e are in communication with the annuli s in the cylinder walls a, b c, that communicate with the atmosphere, and co-act with the inlet ports t, t of the sleeve valves p and q.

The outlet ports u u in the sleeve valves p and q are adapted to register with the cut away edges .1 v of the shoulders formed by the setting back of the liners d and e, and thereby lead to the lower annuli w 20 formed between the liners d, e and the walls of the high pressure cylinders h and Inlet ports :5 2: lead to the high pressure cylinders h and 2 from the similarly formed upper annuli y y.

The lower annulus w on the one side is in. communication with the upper annulus y on the other side of the machine by means of the pipe coil 2 (shown in dash-dot lines on the drawing) disposed in and passing through the water jacket 2 and similarly the lower annulus w on this latter side communicates with the upper annulus y above and on the same side as the annulus w by means of the pipe coil 2' (shown in full lines on the drawing) that also passes through the water jacket 2.

The delivery Valves one of which is shown at 3 are contained in false safety heads 5 and 8 resting on the tops of the high pressure cylinders h and 2'. Water passages I in the cover it are in communication with the jacket 2 by which means a similar cooling of the compressed air is ob tained as is effected by the coils z, z disposed in the main jacket 2.

On the upstroke of the low pressure piston l with the high pressure piston 12 the low pressure air or gas expelled through the ports u and past the cut-away edges 11 into the annulus w passes by the passage 8 into the coil 2 which delivers the air or gas into the annulus 1/ by way of the passage 9. From the annulus y the cooled low pressure air or gas enters the high pressure cylinder 2' by way of the ports at when the piston o is at the bottom of its stroke and is compressed and discharged through the delivery valve in the false safety head 6 on the upstroke of the piston o.

A similar series of operations takes place with respect to the transfer of the low pressure air or gas from the low pressure cylinder 9, and it will be clear that the partially compressed air or gas from the low pressure cylinder of the one pair of cylinders is passed in a cooled condition to the high pressure cylinder of the other pair for compression and delivery and from the low pressure cylinder of the latter pair to the high pressure cylinder of the first pair for compression and delivery and with the combination of the sleeve valve controlling the inlet and discharge as described and the arrangement of the false safety head carrying the delivery valves and the jacketed high and low pressure cylinders a small clearance, very efficient and silent machine running at high speed is obtained.

In order to act as a three stage compressor the two stage construction hereinbefore described may be modified by fitting additional suction or inlet valves to the top of either the high pressure cylinder or-cylinders, or high pressure piston or pistons, or both, through which air or gas compressed in the crank case by the down stroke of the piston or pistons, is supplied prior tothe opening of the ports a: to admit air or gas compressed in the low pressure cylinder or cylinders. Thus compressed air or gas is admitted to the high pressure cylinder or cylinders during the whole of the down stroke of the piston or pistons. The crank case must of course be provided with suction or inlet valves, which must be constructed with each line of motion work separately enclosed.

A compressor modified as described above for three stage compression operates in the following manner:

Air or gas at atmospheric or low pressure is sucked through the suction or inlet valves into the crank case by the up stroke of the piston or pistons. During the subsequent down stroke of the piston or pistons, the air or gas is compressed inthe crank case up to a predetermined relatively low pressure A, when it is forced or passes through the suction or inlet valves into the top of the high pressure cylinder or cylinders. Towards the bottom of the piston stroke the air or gas which has been compressed to an intermediate pressure B, in the low pressure cylinder or cylinders, enters the high pressure cylinder or cylinders through the ports a: in the lower parts of the walls thereof, which have then become uncovered by the high pressure piston or pistons, and compresses the air or gas admitted to the cylinder or cylinders from the crank case at pressure A to its own pressure B without any mechanical aid. The upstroke of the high pressure piston or pistons then compresses the air or gas from pressure B to the final pressure C at which it is discharged through the delivery valve or valves in the head of the high pressure cylinder or cylinders.

What I claim is:

1. A two-stage air or gas compressor comprising a plurality of units each including superimposed high and low pressure cylinders and superimposed high and low pressure pistons in trunk form in said cylinders, an inlet chamber common to and communicating with the low pressure cylinders, an independent inlet chamber for each of the high pressure cylinders, an outlet .chamber for each low pressure cylinder, conduits connecting the outlet chamber of the low pressure cylinder of one unit with the inlet chamber of the high pressure cylinder of the other unit, and a sleeve valve for each unit comprising a tubular element arranged between the low pressure pistons and the low pressure cylinders and formed with a series of openings to be associated with the inlet ports of the cylinders in a predetermined position of the element and an upper series of ports at all times in registry with the outlets of the cylinders, said element operating to control communication between the common inlet chamber and the low pressure cylinder and also serving to control communication between the outlet of each low pressure cylinder of one unit with the inlet of the high pressure cylinder of the other unit. 2. A construction as defined in claim 1, wherein the outlet chamber of the low pressure cylinder of each unit is formed to afford more extended communication between the low pressure cylinder and the outlet of that cylinder than between the low pressure cylinder and the inlet of that cylinder in the operation of the sleeve valve.

3. A construction as defined in claim 1, including Water jackets for the cylinders, the conduits between the outlet of the low pressure cylinder of one unit and the inlet of the high pressure cylinder of the other unit passing through the water jackets.

4. A construction as defined in claim 1, including a pressure controlled outlet valve for each of the high pressure cylinders, said valves being aligned with and directly responsive to the high pressure pistons.

WILLIAM FREDERICK JENNINGS. 

